Fluid motor



May l, 1951 A. c. DARCEY 2,551,246

FLUID MOTOR Filed Jan. 30, 1946 2 Sheets-Sheet l A. C. D'ARCEY May l, 1951 FLUID MOTOR C .ml f.

Filed Jan. 50, 1 946 Patented May 1, 19.51

FLUID MOTOR Alfred C. DArcey, Norwood, Mass., assigner to Bendix Aviation Corporation, Norwood, Mass., a corporation of Delaware Application January 30, 1946, Serial No. 644,287

This invention relates to fluid motors, and parfticularly to uid motors of the servo-type, in which each energization of the motor is for the purpose of moving a work performing element from one to another of its several pre-determined settings-as, for example, the forward, reverse, or neutral position of a clutch or reversing gear.

An object of the invention is to provide a multiple position motor of novel construction, featuring simplicity of arrangement and a minimum number of parts.

Another object is to provide a multiple position motor whose parts are so inter-related as to assure positive action of accurate extent in moving from one position to another, as desired.

Another object is to provide a motor in which accurate positioning is accomplished without relsorting to the use of complicated indexing or latching mechanism.

These and other objects of the invention will become more apparent upon reading the following detailed description of the presently preferred embodiment of the invention, as illustrated in the accompanying drawings. It is to be underf stood, of course, that the drawings are illustrative only, as the invention embraces other embodiments within the scope of the appended claims.

In the drawings, Figure 1 is a schematic representation of a hydraulic system embodying the present invention;

Figure 2 is a sectional view on a larger scale, Showing the moving parts in the positions assumed when the device to be actuated is in one of its three possible settings; and

Figures 3 and 4 are views similar to Figure 2, but showing two other possible settings.

Referring to these drawings, wherein like reference characters designate the same part throughout the several views, the characters I and II designate a pair of cylinders disposed in tandem relationship, with the smaller cylinder I I integrated with or rigidly secured to the larger cylinder I0, so that the two have a common dividing wall I2 through which there extends a hollow tube or rod I3 carrying at one end a piston I4 and at the other end one or more stop elements I5, I6 threaded to the threaded end portion of the rod I3, for a purpose to be more fully explained. A second piston, i8, is slidable in the larger cylinder E9, and is integrated with a rod I 9 extending through the outer wall 20 of the larger cylinder and having operative connection with the device 2l to be actuated. Such device 2I may be the reversing gear of a marine engine, or any other power or directional control 2 Claims. (Cl. 121-38) 2 that is shiftable to any one of a plurality orsettings. Three-way valves 3l', 32, 33 (Figure l) control flow of uid to and from ports 34, 35, 36, of the cylinders I0 andi I; the pump for the uid being indicated at 4I in Figure 1, and the reservoir at 42. Y

For theA ahead, or most extended position of the rod I9 (Figure 4), hydraulic pressure is applied to ports 35 and 36, which pressure acts o n the back or reverse faces of pistons I4 and I8. This pressure drives piston I8 to'its extreme or full ahead position and also drives piston I4 forward until the locknut or adjusting nut hits the partition I2 between the two cavities of the cylinders. function except to put piston I4 in position for the next operation or hold it in place from the preceding operation (Figure 3).

To go into the neutral or mid position (Figure 3) pressure is applied to ports 34 and 35 and re lieved at port 36. The pressure entering port 34 acts on the front or ahead face of piston I8 drivingit in the reverse direction. The uid trapped between pistons I4 and I8 is exhausted through the central bore in the rod I3, then out through port 36, permitting piston I 8 to come up against piston I4; piston I4 then restricts further movement of pistonv I8 by virtue of the fact that 'although the forward face of piston I4 and the rear face of piston I 8 are subject to the-same fluid pressure, the rod of piston I8 is larger in diameter than the rod of piston I 4 and consequently presents less effective area to the pressure exerted, and therefore less force.

The piston rod of piston I4 extends through a partition I2. Carried on the end of the piston rod are the adjustable nuts I5, I6, the purpose of which is to adjustably limit the most forward or ahead position of piston I4, thus making adjustable the mid or neutral position of the devlce.

To go into the reverse, or least extended, position of the cylinder fluid pressure is applied to port 34 and exhausted from ports 35 and 36. This permits the pressure on the front or ahead face of piston IB to drive it and piston I4 into the reverse or astern position (Figure 2).

To go into the mid or neutral position again fluid pressure is applied through ports 34 and 3F. The diiferential area in favor of piston I4 previously mentioned permits it to drive in the forward or ahead direction, forcing piston I8 along with it despite the fact that the same fluid pressure may be exerted on the forward or ahead This latter operation performs no useful- 'cylinder determines-the directionof mot-ion and` ultimate. position cf'theY piston-rod of.' piston*4 I8, from which motion power can be taken for the purpose of operating a marine reverse gear 212 or performing any other function where three positive positions are required.

The valves 3|, 32, and 33-may be operateddi rectly, or by remote control', as by@ electricl switches in the circuits leading to the solenoid windings of the valves; if theV valves are of a solenoid type.

A by-pass valve, for pressure relief purposes, may be inserted across lines 62 and G3, as indicated at6|-.V Also-,- af lter 64- may be inserted in return line 63'for uid cleaning purposes.

VWhere specific-speed or power differentialsfare desired, in moving from one predetermined posi-` tionI to` another, thesecan` bey obtained by use of4 the concept disclosed therein of providing dif#- ferential effective areas on opposite sides of the pistonA I8. Byvarying-z` the degreeof` difference inthescfhrespectiv-eA areas; any;r desired' ratio of power ditferential .maybe' effected',-

What-is claimed-is: Y

1-.I n a device of'the class described, a pair ofl cylinders intandenr relationship having a com-- mon en d wall, Va` pairof pistons arranged end to-end in-one of; saidl cylinders, ahollow' rodconnectedto one ofthe pistons and extending' through-said common end wall intol the other cylinder so as to communicate the-space-formed in said one cylinder between the adjacent ends ofsaid piston with the othercylinder, an adjustable element'carriedby said rodfor engagement withsaidl common end wall-A tolimit the'- movement-of said oner piston in one direction, saidf other pistonadapted. to be. connected tofal memberfor moving the same-to three-positions,- means-forconnecting one endv ofL said one cylin der toafluid pressure source and the other end of saidf one cylinder andsaid other cylinder toexhaust to. cause said other pistonto assume one? position; means. for connecting both endsofi said one cylinder to said source and said other cylinder to exhaust to cause said other piston to assume a second position, and means for connecting said one end of said one cylinder to exhaust and said other end of said one cylinder and said other cylinder to said source to cause said other piston to assume a third position.

2. In a device of the class described, a pair of cylindersf in tandem relationship having a common end wall, aiv pair of? pistons arranged end to end in one of said cylinders, a hollow rod connetted to one of the pistons and extending through said common end wall into the other cylinder so as to communicate the space formed inl saidon'e cylinder between the adjacent ends of: said?v pistonY with the other cylinder, an adjustablefelein'entv'carried by said rod for engagement with said common end wall to limit the movene'nt of s'aiii' one piston in one direction. said-f other" piston adapted to be connected to a member for moving the same to three positions, the effective areasof the adjacent ends of the pistons-.being-.equal and thefeifective areas of the remote end of--said-one piston being greater than the effective area ofthe remote, end. of said other piston,v means for connecting one end of sa-idone cylinder to a fluid rpressure source and the other end A.of saidone cylinder and said other cylinder to exhaust to causesaidother piston to assume onerposition,.means for connecting both ends of saidone cylinder to said source and said other cylinder to exhaust to cause. saidv other pistonto assume a second position, and means for connecting said one end of saidone cylinder tol exhaust and saidother end of said one cylinder and said other cylinder to said source to cause said other pistonh to assumev aV third position.

ALFRED C. DARCEY.

REFERENCES CITED The following references are of record in the flle of' this. patent:

UNITED STATES- PATENTS Number y Name Date 833,631 Rhodes Oct. 1'6, 1906 2,005,387 Pelton --.June 18, '1935 2`,095,820 Lenz Oct. 12, 1937 2,244,770 Englesson June A10,1941 2,401,197 Simpson May 281946 

